CSRR-loaded UWB monopole antenna with electronically tunable triple band-notch characteristics for cognitive radio applications

摘要

This article introduces a compact configuration of printed monopole antenna with electronically tunable band-notched function for ultra-wideband (UWB) applications. A partially grounded rectangular shaped monopole is designed initially to achieve UWB behavior. The notch characteristics are then introduced by employing three complementary split-ring resonators (CSRRs) on the radiating surface. The proposed antenna exhibits an ultra-wide operating band ranging from 1.98 to 10.54 GHz with the notched frequencies at 2.37, 3.03, and 4.18 GHz, respectively. In order to accomplish versatility in the antenna operation, the notched frequencies are controlled electronically by implementing three varactor diodes in between the split-ring slots. By applying an appropriate reverse bias voltage, the triple notched bands are tuned over the frequency bands: 1.58-2.12 GHz, 2.24-2.68 GHz, and 3.08-3.78 GHz, respectively. A prototype with an overall dimension of 34.9 x 31.3 x 1.6 mm(3) has been fabricated to experimentally determine the tuning capability of the antenna structure. The experimental result establishes close correspondence with the simulated antenna properties. The suggested antenna can be implemented practically to reject interferences from complete 1.5-2.1 GHz LTE systems, and 2.5/3.5 GHz-WiMAX bands, simultaneously. The capability of tuning three notched-bands together is distinctive and has not been reported in the published literature to the best of authors' knowledge.